1. Field of the Invention
The present invention relates to a process for recovering energy from substances having a high temperature and in particular to a process for recovering energy from molten slag material obtained in metallurgical processes.
2. Description of the Prior Art
Molten slag material produced in blast furnaces and in phosphor furnaces, having a temperature of 1200.degree. C., is in the prior art cooled by means of water, thereby producing steam. Said steam being released, however, in a rather large space, cannot be used economically.
As molten slag material arrives at a temperature of about 1200.degree. C. from the blast furnace into a pit through a refractory brick gutter, this heat might be recovered by applying steel instead of refractory brick gutters and by cooling said steel gutters by means of a circulating liquid energy absorbing fluid, such as for example water. When draining off said molten slag material, liquid iron might be entrained from time to time, however. Said liquid iron would burn immediately through said steel gutters, which might cause an explosive contact between the liquid iron having a high temperature, and the circulating water. Although instead of water, for example a liquid silicon oil could be employed, no improvement will occur in the latter case, as then the explosive reaction would take place between said silicon oil and the liquid iron.
French Pat. No. 2,345,664, entitled "Recovering heat from molten metal slag from metallurgical treatments" issued to Kawasaki Yukogyo Kabushiki Kaisha on Oct. 10, 1977 teaches the recovery of radiation heat from molten slag by positioning metal tubes over the molten slag, radiation heat is absorbed by water flowing through these tubes. The difficulty with this method is that it is disadvantageous, as the tubes must be held at important distances from the slag, in order to avoid damage to the tubes. Moreover, no optimum recovery of radiation heat is obtained.
French Pat. No. 578,633, entitled "Coal gas, heating, cooling, ventilation", issued to Johann Heinrich Stein on Oct. 1, 1924 teaches a method to recover radiation heat from slag material by means of water present in a hollow container. This method presents the same disadvantages as mentioned hereinbefore.
U.S. Pat. No. 2,038,765, issued to Frank L. Shahan on Apr. 28, 1936, entitled "Heat filter device" teaches the recovery of radiation heat from slag material by means of water present in tubes. The difficulty with this device is that the tubes are surrounded by a layer of clay material both as an insulator and for absorbing and storing heat. Much radiation heat is lost by this layer.
U.S. Pat. No. 1,585,982, issued to Joshua K. Clutts on May 25, 1926, entitled "Blast furnace" teaches the recovery of heat from slag material by means of a boiler. The difficulty with this device is that much radiation heat is lost in this way.
British Pat. No. 195,267, issued to Sulzer Freres S. A. on Apr. 19, 1929, entitled "Process and apparatus for the pouring and cooling of castings" discloses the recovery of heat from slag material by means of a boiler. The difficulty with this process is that much radiation heat is also lost here.